1. Field of the Invention
This invention relates to electric switches and, more particularly, to electric switches of the snap action type.
2. Statement of the Prior Art
Snap action switches are frequently used to control the starting and stopping of electric motors which operate pumps in response to the rise and fall of the level of water or other liquid. The rise and fall of liquid in sumps occurs at unpredictable rates which may also vary during the rise and fall. Normally, floats, connected with a switch operating lever or other means, will cause the separation and engagement of contacts to connect and disconnect the pump motor. The switch opening and closing movements, quite desirably, occur with a snap. Such snap action minimizes arcing at the contacts and thereby prolongs switch life.
Prior art snap action switches have several shortcomings. Those shortcomings arise, in part, because of the adverse conditions under which the switches are frequently employed. The presence of moisture causes contamination and failure of lubricated hinge joints. High inrush current and high temperature conditions form high resistance junctions at hinge joints in the current path which lead to base and cover meltdown and hazardous failure. Hinge joints are also susceptible to mechanical wear. As all prior art snap action switches have hinged joints, which may be lubricated, in the current path, all prior art snap action switches suffer, to some degree, the shortcomings outlined above.